Heat transfer or cooling schemes often include one or more heat sources that need to be cooled. Heat sources may include components such as electronic components or materials such as lubrication oils. Generally, heat from these one or more sources is transported to one or more heat sinks so that the source(s) may be cooled. In the gas turbine sector, a common heat sink employed is the gas turbine fuel. That is, heat from heat sources are often transferred into the gas turbine fuel. However, with conventional cooling schemes, thermodynamic properties often create limitations on the cooling schemes. For example, when conventional cooling practices are followed, to transfer heat from a source to a sink, the source is generally at a higher temperature than the sink. Furthermore, as heat load increases (i.e., that amount of heat being transferred), the temperature difference between the source and the sink generally increases.
To obtain these differences in temperatures between the fuel and heat sources so that the heat load demand can be met, restrictions or limitations are often put on the maximum fuel temperatures so that the fuel can be effectively used as a heat sink for components of the engine. In other words, a fuel temperature is set so that the temperature difference between the heat source and the heat sink (i.e., the fuel) is sufficient to reject the heat load. The manner in which this is often accomplished is by minimizing the heat load on the fuel. That is, the amount of heat sources that will use the fuel as a heat sink is minimized, or at least a limit is placed on how much heat these sources can convey to the fuel, so that the fuel temperature does not go over a predetermine temperature. As such, the fuel can still effectively cool important engine components. Often, this means minimizing the functionality of electrical systems so they do not over-utilize the fuel as a heat sink. Alternatively, mission capability may be limited to, for example, to maintain acceptably low fuel tank temperatures.
Accordingly, there is room for improvement in this area.